"Alone in the Universe" by John Gribbin - Atheist Nexus2015-03-03T23:34:35Zhttp://www.atheistnexus.org/forum/topics/alone-in-the-universe-by-john-gribbin?groupUrl=originsuniverselifehumankindanddarwin&commentId=2182797%3AComment%3A2137855&xg_source=activity&groupId=2182797%3AGroup%3A109911&feed=yes&xn_auth=noWith all due respect, I am do…tag:www.atheistnexus.org,2013-01-26:2182797:Comment:21526442013-01-26T22:35:19.691ZROMAN ROMACHhttp://www.atheistnexus.org/profile/ROMANROMACH
<p>With all due respect, I am down on memetics big time. So I will recuse myself from the discussion.</p>
<p>With all due respect, I am down on memetics big time. So I will recuse myself from the discussion.</p> Of course you can reject a pa…tag:www.atheistnexus.org,2013-01-26:2182797:Comment:21525502013-01-26T21:09:24.565ZJoseph Phttp://www.atheistnexus.org/profile/JosephP
<p>Of course you can reject a paradox, if you don't think that there are sufficient problems with the proposition for it to be a paradox.</p>
<p>What I don't buy is his assumptions that make it a paradox. Thus, I reject the paradox.</p>
<p>Time is not sufficiently vast, on a logarithmic scale, relative to the size of the galaxy, after you account for a few things, such as the synthesis of elements higher than hydrogen and the formation of later generation stars and planets that are capable of…</p>
<p>Of course you can reject a paradox, if you don't think that there are sufficient problems with the proposition for it to be a paradox.</p>
<p>What I don't buy is his assumptions that make it a paradox. Thus, I reject the paradox.</p>
<p>Time is not sufficiently vast, on a logarithmic scale, relative to the size of the galaxy, after you account for a few things, such as the synthesis of elements higher than hydrogen and the formation of later generation stars and planets that are capable of generating life.</p> The Fermi Paradox is not some…tag:www.atheistnexus.org,2013-01-26:2182797:Comment:21523642013-01-26T20:51:08.715ZJoshua Colwellhttp://www.atheistnexus.org/profile/JoshuaColwell
<p>The Fermi Paradox is not something that can be rejected. It is a statement of fact: there are no extraterrestrials here. The "paradox" part comes from recognizing that while the Milky Way is vast, time is more vast. At very modest fractions of the speed of light, a sufficiently technologically advanced civilization could completely colonize the galaxy in a tiny fraction of the age of the galaxy. That has not happened. Fermi was saying, "why not?". There are many possible explanations, but…</p>
<p>The Fermi Paradox is not something that can be rejected. It is a statement of fact: there are no extraterrestrials here. The "paradox" part comes from recognizing that while the Milky Way is vast, time is more vast. At very modest fractions of the speed of light, a sufficiently technologically advanced civilization could completely colonize the galaxy in a tiny fraction of the age of the galaxy. That has not happened. Fermi was saying, "why not?". There are many possible explanations, but the vastness of space is not one.</p> ... but I think Fermi was spe…tag:www.atheistnexus.org,2013-01-26:2182797:Comment:21526252013-01-26T20:49:34.076ZJoseph Phttp://www.atheistnexus.org/profile/JosephP
<blockquote><p>... but I think Fermi was speaking of life that was superior in intelligence and technology.</p>
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<p><a href="http://en.wikipedia.org/wiki/Fermi_Paradox" target="_blank">http://en.wikipedia.org/wiki/Fermi_Paradox</a></p>
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<p>He was speaking about intelligent species that have achieved interstellar travel, as we could possibly do, in another couple hundred years or so, if we don't wipe ourselves out, before then.</p>
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<blockquote><p>On this point…</p>
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<blockquote><p>... but I think Fermi was speaking of life that was superior in intelligence and technology.</p>
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<p><a href="http://en.wikipedia.org/wiki/Fermi_Paradox" target="_blank">http://en.wikipedia.org/wiki/Fermi_Paradox</a></p>
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<p>He was speaking about intelligent species that have achieved interstellar travel, as we could possibly do, in another couple hundred years or so, if we don't wipe ourselves out, before then.</p>
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<blockquote><p>On this point I agree with him that it probably doesn't exist. If life is DNA-based, then evolution would operate under the same principles as it does on earth. Since we now live in societies in which survival is no longer a life-and-death struggle, there is no selective pressure for us to get any smarter. The same would go for an alien life form.</p>
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<p>What you're missing is that genetic evolution doesn't matter anymore (or at least matters very little), in our evolution as a species. Our memetic evolution is what will eventually lead us to an interstellar culture or cause us to wipe ourselves out.</p>
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<p>Also, he's not saying that other intelligent life doesn't exist in the galaxy. He's saying that if other intelligent life exists in the galaxy, the estimates (such as the Drake equation) have problems. That's why it's a paradox.</p>
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<p>Personally, I think most of the problems with the estimates have to do with underestimating the difficulties of interstellar travel and overestimating the effective age of the universe, in terms of how long interstellar civilizations would have been around, and how freely they would be able to move throughout the galaxy.</p>
<p>Part of the problem is that he assumes an effectively limitless time for colonial expansion, relative to the age of the universe. I don't think that the relative differences in time are quite as exponential as he assumes.</p>
<p>I went through most of that back on page one.</p>
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<p>I think that at the more pessimistic end of the estimates, with the limitations of space travel factored in, it's not so hard to believe that we haven't had anyone probing us yet.</p> I agree with you that there m…tag:www.atheistnexus.org,2013-01-26:2182797:Comment:21525472013-01-26T20:05:34.586ZROMAN ROMACHhttp://www.atheistnexus.org/profile/ROMANROMACH
<p>I agree with you that there must be abundant life out there, but I think Fermi was speaking of life that was superior in intelligence and technology. On this point I agree with him that it probably doesn't exist. If life is DNA-based, then evolution would operate under the same principles as it does on earth. Since we now live in societies in which survival is no longer a life-and-death struggle, there is no selective pressure for us to get any smarter. The same would go for an alien life…</p>
<p>I agree with you that there must be abundant life out there, but I think Fermi was speaking of life that was superior in intelligence and technology. On this point I agree with him that it probably doesn't exist. If life is DNA-based, then evolution would operate under the same principles as it does on earth. Since we now live in societies in which survival is no longer a life-and-death struggle, there is no selective pressure for us to get any smarter. The same would go for an alien life form.</p>
<p>Once they reached a comfortable, secure technological point there would be nothing requiring them to get larger brains than they have now. So, they would probably be just like us -- wondering why they haven't been visited by a technologically superior culture.</p>
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<p> </p> How do I determine the odds o…tag:www.atheistnexus.org,2013-01-26:2182797:Comment:21523102013-01-26T19:06:42.097ZJoseph Phttp://www.atheistnexus.org/profile/JosephP
<p>How do <strong><em>I</em></strong> determine the odds of any given extrasolar-planet evolving life? I don't. I have no freaking clue.</p>
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<p>The only real statements that I can make are that there are a <strong><em>huge</em></strong> number of planets out there with life on them, because of the sheer numbers involved. I made a lot of approximations, based upon other people's numbers, to explain why I reject the Fermi Paradox, back on page one of this discussion. I can only make…</p>
<p>How do <strong><em>I</em></strong> determine the odds of any given extrasolar-planet evolving life? I don't. I have no freaking clue.</p>
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<p>The only real statements that I can make are that there are a <strong><em>huge</em></strong> number of planets out there with life on them, because of the sheer numbers involved. I made a lot of approximations, based upon other people's numbers, to explain why I reject the Fermi Paradox, back on page one of this discussion. I can only make the most general sorts of conclusions, with my knowledge of the field.</p> Thanks. How do you determine…tag:www.atheistnexus.org,2013-01-26:2182797:Comment:21524442013-01-26T18:51:26.425ZROMAN ROMACHhttp://www.atheistnexus.org/profile/ROMANROMACH
<p>Thanks. How do you determine the odds of life being on any one planet? We do not have any sampling data. If your talking total mass of life, that's one thing, if you're talking odds, that's another.</p>
<p>From our perspectve it's easy to determine that Mars is not quite in the Zone. How easy is it to ascertain from 20 lightyears distance. We have not explored the ice cap(s) on mars yet, neither have we drilled a deep core sample. On earth we have life forms living miles beneath the…</p>
<p>Thanks. How do you determine the odds of life being on any one planet? We do not have any sampling data. If your talking total mass of life, that's one thing, if you're talking odds, that's another.</p>
<p>From our perspectve it's easy to determine that Mars is not quite in the Zone. How easy is it to ascertain from 20 lightyears distance. We have not explored the ice cap(s) on mars yet, neither have we drilled a deep core sample. On earth we have life forms living miles beneath the surface. So, there is much more to learn. </p>
<p></p> The point I was making was th…tag:www.atheistnexus.org,2013-01-26:2182797:Comment:21525382013-01-26T17:30:17.477ZJoseph Phttp://www.atheistnexus.org/profile/JosephP
<blockquote><p>The point I was making was that the total number of planets is meaningless.</p>
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<p>Umm, no, it's not meaningless. When we're talking about a statistical likelihood of there being life on other planets, the planetary density of the galaxy and the universe is very much at issue.</p>
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<blockquote><p>Additionally, Mars may have had life, but no longer seems to, even though it has ice at the caps. Might it have fallen into that zone? It's all a matter of…</p>
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<blockquote><p>The point I was making was that the total number of planets is meaningless.</p>
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<p>Umm, no, it's not meaningless. When we're talking about a statistical likelihood of there being life on other planets, the planetary density of the galaxy and the universe is very much at issue.</p>
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<blockquote><p>Additionally, Mars may have had life, but no longer seems to, even though it has ice at the caps. Might it have fallen into that zone? It's all a matter of degrees.</p>
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<p>Mars is a little outside of that zone. It is too far away from the sun for the energy from the sun to maintain its temperature within the necessary range for a long enough period of time. Obviously, it passed through the necessary temperature range, at some point in its life-cycle, going from molten, after formation, to its current, relatively inert stage. There was quite possibly very simple life, at some point, but the window of time was too short for that life to evolve very much.</p>
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<p>Mars might heat up significantly, after the sun goes into the red giant phase, in another 5 or 6 billion years, but that phase will be far too short of life to reform and evolve any amount worth speaking of. Plus, Mars and the outer plants might escape, during that period, in which case, it won't be warming, as it goes hurtling off into interstellar space.</p> Thanks. The "Goldilocks Zone"…tag:www.atheistnexus.org,2013-01-26:2182797:Comment:21525222013-01-26T16:48:15.275ZROMAN ROMACHhttp://www.atheistnexus.org/profile/ROMANROMACH
<p>Thanks. The "Goldilocks Zone". The point I was making was that the total number of planets is meaningless. Additionally, Mars may have had life, but no longer seems to, even though it has ice at the caps. Might it have fallen into that zone? It's all a matter of degrees.</p>
<p>Thanks. The "Goldilocks Zone". The point I was making was that the total number of planets is meaningless. Additionally, Mars may have had life, but no longer seems to, even though it has ice at the caps. Might it have fallen into that zone? It's all a matter of degrees.</p> He's not speaking of life on…tag:www.atheistnexus.org,2013-01-26:2182797:Comment:21519062013-01-26T04:28:42.908ZJoseph Phttp://www.atheistnexus.org/profile/JosephP
<p>He's not speaking of life on other planets within our solar system. None of the other planets in our solar system fit the necessary criteria for DNA-based life. He's speaking of chemically-similar life on planets within similar orbits of <strong><em>other</em></strong> stars.</p>
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<p>There are a couple hundred billion stars within our galaxy alone. Some of them must have suitable planets at orbits that are the appropriate distance to contain liquid water.</p>
<p>He's not speaking of life on other planets within our solar system. None of the other planets in our solar system fit the necessary criteria for DNA-based life. He's speaking of chemically-similar life on planets within similar orbits of <strong><em>other</em></strong> stars.</p>
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<p>There are a couple hundred billion stars within our galaxy alone. Some of them must have suitable planets at orbits that are the appropriate distance to contain liquid water.</p>